1. Field of the Invention
The present invention relates to a haemostatic material. Haemostatic materials are useful, for example, in reducing or stopping bleeding of a physiological target site in a person or animal. The material can also be used to stem bleeding during medical procedures.
2. Background of the Related Art
There are many circumstances in which animals, both human and non-human, may become injured or wounded causing bleeding. In the case of minor wounds, the bleeding may be stemmed by the natural haemostatic mechanisms of the body which lead to coagulation of the blood to form solid clots which prevent hemorrhage and aid repair of damaged blood vessels. Basic first aid may be administered in some cases to stem blood flow and assist wound healing, such as stemming blood flow in a patient by the application of continuous pressure to a wound. This enables clotting factors to collect at the site of the wound and form a congealed blood mass to stem blood flow. However, this technique is not suitable for severe wounds and wounds having multiple bleeding points. Therefore, bleeding out continues to be a major cause of death.
Death caused by bleeding out is a particular problem in environments such as battlefields. Typically, wounds arising in such situations are accompanied by significant bleeding, and many result in death. Bleeding out is also a significant cause of death amongst the civilian population following trauma injuries.
In attempts to provide products which facilitate the stemming of blood flow from a wound, haemostatic products have been developed.
Haemostatic agents are typically presented in the form of solid powders or granules, or as liquids. All of these forms, being flowable, provide for good contact with the irregular surfaces which are typical of wounds so that good haemostasis can be achieved. However, the flowable nature of particulate of liquid haemostatic agents also renders them relatively difficult to handle in use. It can be a problem to retain the flowable haemostatic agent at the wound site where the stemming of blood flow is required.
These agents include a product sold under the brand name QuikClot®. QuikClot® comprises a zeolite compound which absorbs water from the blood flowing from a wound such that the clotting factors present in the blood become concentrated and the blood coagulates more quickly, so the zeolite and the coagulated blood together form a coagulum to stem blood flow.
In a development of this product, a gauze bag is provided in which the haemostatic agent is contained. Whilst this improves the ease of handling and application of the haemostat, the gauze bag physically separates the haemostat from the body tissues and blood at the wound site. This reduces the efficacy of the haemostat. Further, although the gauze bag is flexible, the particles of haemostatic agent are unable to move outside the bag and into any crevices or irregular surfaces of the wound, as the holes in the gauze bag are smaller than the typical particle size of the haemostatic agent retained in the gauze bag. The gauze bag remains in situ until removed.
A further product is described in WO 02/102276. The product is a flat single piece sheet dressing comprising a chitosan layer. It does not include granules or flakes as the wound contact layer. The dressing is applied to the site of a wound and forms a seal. The chitosan causes the blood to coagulate which together with the seal formed by the sheet stems the blood flow. However, such products must be applied directly to the source of bleeding, i.e. to an artery. Such application requires skill and accuracy. Military medics and first responders do not have the necessary skills to identify the source of bleeding and apply the dressing thereto. In any event, it would be extremely difficult to perform such a delicate operation on a battlefield or at a trauma site. In addition, when the sheets according to WO 02/102276 are removed, bleeding restarts as the sealing layer is removed.
GB 2095995 and GB 2129300 disclose the use of pure chitosan acetate as a haemostatic material. However, the gel which forms from the pure salt is very thin as only the outermost surface of the material is available to act in a short period of time. Quite often this material fails to stop bleeding and even when it does, the clot is very thin and weak so that when the patient is moved, the clot is compromised and bleeding resumes.
Therefore, it is an object of the present invention to provide a haemostatic material which stems the flow of blood from a physiological target site relatively quickly and which is easy and safe to use.